Displays only on the target standby database when it is SYNCHRONIZED with or is TARGET UNDER LAG LIMIT of the primary database, has connectivity to the observer, but the primary database does not have a connection to the observer. Transitions the target standby database into the primary role, opens the new primary database in read/write mode, and starts redo transport services. expires. Refer to the appropriate Oracle RAC or Oracle Restart documentation for further information. Verify Before Switch-over: See Oracle Enterprise Manager Command Line Interface. Ideally the primary, standby, and observer will be in geographically separate areas. Any apply delay must be removed before beginning a switchover. file (fsfo.dat). A fast-start failover to the target standby database fails. observer name, host, whether it is the master observer, when it became the master For Oracle RAC databases, see Oracle Real Application Clusters Administration and Deployment Guide for more information about configuring database services with the SRVCTL utility. Now that we know switchovers work, it's time to test failovers. The word manual is used to contrast this type of failover with a fast-start failover (described in Fast-Start Failover). When enabled, re-create the standby database. If the observer is stopped abnormally (for example, by typing CTRL/C), restart it and reference the existing fsfo.dat file with the FILE IS qualifier. Unlike ORLs, SRLs should be created with only one member per group. The FS_FAILOVER_OBSERVER_PRESENT column, which indicates whether the observer is running and actively pinging the database. the location of the observer log file, and the location of the observer runtime data A switchover is a role reversal between the primary database and one of its standby databases. DGMGRL can be used to manage multiple observers in a group of broker configurations. On Windows, the directory specified by the DG_ADMIN select name,open_mode,database_role from v$database; Note: The guide makes few assumptions about your existing environment and includes examples for creating a physical standby database and Data Guard Broker configuration. It is instructive to watch the alert logs on both databases as well as the observer log after aborting the primary to gain insight into what happens during FSFO failover. The name of the callout configuration scripts is specified in If it exists, and it contains a pre-callout script location, Note that the database will not open at this point. To stop the observer when fast-start failover is enabled, the primary database and target standby database must be connected and communicating with each other. Use the FastStartFailoverTarget configuration property on the current primary database to specify one or more fast-start failover targets. committing because a fast-start failover may have occurred while it was If the service has been configured to start automatically (-policy AUTOMATIC), then the service will automatically start only after a database role change. ConfigurationSimpleName represents If the database is managed by Oracle Clusterware, broker does not open any pluggable Perform SWITCH LOGFILE if necessary. For more details about managing Redo Apply services using properties, see Managing Log Apply Services. But before enabling Flashback Database, you must enable Flash Recovery Area (FRA). Failing over the database won't do much good if applications and other database clients don't know where the primary went. failover configuration file, this script is run. Dataguard Switchover Using DGMGRL A switchover is a role reversal between the primary database and one of its standby databases. Tags: Data Guard, Oracle. A complete failover also attempts to avoid disabling any standby databases that were not the target of the failover, so that they may continue serving as standby databases to the new primary database. the SYSDG or SYSDBA privilege. Now your old standby database is become primary database, it is highly recommended to consider immediate full backup of primary database. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. When you configure data guard using OCI console, the default mode is set to maxprotection. Automatic failover is optional and can be enabled or disabled on your Autonomous Container Databases with Autonomous Data Guard. Starting the Observer Using Cloud Control. created when the START OBSERVER command is issued. To configure fast-start failover in observe-only mode: Fast-start failover will not be triggered if the primary or standby database is shut down normally. You must then re-create it from a copy of the new primary database and reenable it as described in How to Re-create and Reenable a Disabled Database. SQL> select name,open_mode,database_role from v$database; NAME OPEN_MODE DATABASE_ROLE --------- -------------------- ---------------- MYTEST MOUNTED PHYSICAL STANDBY Step 2: Apply the following command to finish database recovery. observers for a single Data Guard configuration. Each group that you define must have at least one broker configuration. If block change tracking is enabled on the primary, and the target Create a trigger on this event to perform actions specific to your environment after a switchover or failover, such as updating the name resolution service to point to the new primary. Upon detecting the break in communication, the observer attempts to reestablish a connection with the primary database for the amount of time defined by the FastStartFailoverThreshold property before initiating a fast-start failover. After the conversion, the broker will start Redo Apply to apply accumulated redo data, before failing the database over to the primary role. Steps for FAILOVER the Dataguard environment Without the credentials, Broker will complete the role transition, but will leave the databases in need of a manual restart. So SALESRW will start on CHICAGO (which is now the primary) and SALESRO will start on BOSTON (which is now the physical standby). For information about enabling fast-start failover, see Enabling Fast-Start Failover. If fast-start failover is initiated, the master observer verifies the target standby database is ready to fail over to the primary database role. A switchover is a role reversal between the primary database and one of its standby databases. The remaining Data Guard-related parameters will be set by Broker later in the walkthrough. It doesn't consider how much of that redo has been applied. If the value is non-zero, failover is possible any time the standby database's apply FastStart Failover Ensues: Disaster strikes the primary database and its network connections to both the observer and the target standby database are lost. Database dismounted. configuration file exists. OBSERVER command, if this directory does not have the Attempt to open the primary database, or the following error may be returned: This error may return if the fast-start failover validity check fails or does not complete in under two minutes. Always try to perform a complete failover first unless redo apply has stopped at the failover target due to an ORA-752 or ORA-600 [3020] error. PDBs. You can use the broker's reinstate capability to make a failed primary database a viable standby database for the new primary. The default value is ALL. change tracking enabled, broker enables block change tracking on the new Figure 6-1 shows the relationships between the primary database, target standby database, and observer during fast-start failover: Before Fast-Start Failover: Oracle Data Guard is operating in a steady state, with the primary database transmitting redo data to the target standby database and the observer monitoring the state of the entire configuration. To restore your original disaster-recovery solution after switchover to a logical standby database or after failover to any standby database, you may need to perform additional steps. File. If the currently configured mode is maximum protection, Cloud Control will downgrade the mode to maximum availability. Learn how to use Oracle Data Guard broker to manage databases during switchover and failover. After a failover, the broker publishes Fast Application Notification (FAN) events. collections and databases Set up replica sets and automatic failover in MongoDB Use sharding to scale horizontally, and learn how . You can manually stop a specific observer or all observers. Using Shared Server (MTS) or connection pooling can result in unpredictable behavior. If the target is a snapshot standby database, the broker first converts the database back to a physical standby and then starts Redo Apply to apply all the accumulated redo before completing the failover and opening the database as a primary database. This specifies how often the observer establishes a new connection to the primary database. For this build, we will use a single physical standby database. When fast-start failover is disabled, no observer is called the master observer; all observers have the same functionality. Alternatively, if you intend to switch back to the original primary relatively soon, then you may re-enable the disabled standby databases after the switch back. Use the oraenv script provided by Oracle. It is actually a low-footprint OCI client built into the DGMGRL CLI (Data Guard Broker Command Line Interface) and, like any other client, may be run on a different hardware platform than the database servers. This time, if all the sessions that are connected though the active services Such preparation includes: Ensuring that standby redo log files are configured on the primary database. This section describes how to configure and verify each prerequisite. The primary database, it attempts to disable fast-start failover on as many databases in the configuration with which it has a network connection. Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. The walkthrough begins with a single database that will become the primary of a Data Guard configuration. file, observer runtime data file (fsfo.dat), fast-start failover callout To help you select an appropriate switchover or failover target, use the following DGMGRL commands which perform checks on the database to determine its readiness to complete a role change. Once the observer is started, you cannot change the file's name and location. It's good practice to use separate listeners for application connections and Data Guard connections. computer, it automatically starts the observer when you enable Manual failover gives you control over exactly when a failover occurs and to which target standby database. Specifying Preferred Observers Based on Current Primary. If you expect the network to be disconnected for a long time and learning with R and Python are also covered in this step-by-step tutorial. observer_hostname.log. Oracle 12c-Step by Step Manual Data Guard Failover. observer. Starting Observers as Background Processes. When you are experiencing network disconnections and you issue the DISABLE FAST_START FAILOVER FORCE command on the primary database or a standby database that does not have connectivity with the primary database, fast-start failover may not be disabled for all databases in the broker configuration. If you do not want to use the default, you can define a specific group. FSFO can provide substantial gains in high availability and disaster recovery preparedness for all environments, from inexpensive Cloud-based systems to global distributed data centers. On the Oracle Data Guard Overview page, click Database must be reinstated. Determines whether or not any standby databases that did not participate in the failover operation have applied redo data beyond the new primary database, and thus need to be disabled. command on the observer computer: The observer is a continuously executing process that is See Prerequisites for more information. If both of those observers are unavailable, the observers Managed recovery process has been stopped between primary and standby database and standby becomes primary database. FB Group:https://www.facebook.com/groups/894402327369506/ the service configuration. See Disabling Fast-Start Failover. A far sync instance or Zero Data Loss Recovery Appliance is not a database and therefore cannot be the target of a role transition. The general approach seems to be CDB level failover to standby , so the failover takes place at CDB to CDB , in an event where a single PDB is experiencing an issue , we will have to failover the whole instance ..this will impact all PDB's on the CDB. Set this property for the primary and target standby database if you want the observer to use a different connect identifier than that used to ship redo data (that is, the connect identifier specified by the DGConnectIdentifier property). Default value is 10 miliseconds. It provides a way to quickly restore a database to a previous point in time or SCN using on-disk data structures called flashback logs. To use a far sync instance with fast-start failover, the far sync instance transport mode must be set to either SYNC or FASTSYNC and the target standby database transport mode must be set to ASYNC. Maximum Availability mode uses synchronous redo transfer and FSFO imposes the additional requirement that the redo is recorded in the standby redo log (SRL) of the target standby (AFFIRM option of log_archive_dest_ n). For more information, see START OBSERVER IN BACKGROUND. Have a means of notifying someone if standby apply falls too far behind. Oracle Data Guard Concepts and Administration provides information about setting up the databases in preparation of a switchover. It is very much useful, when the organization has multiple standby sites. In a Managed Instance with multiple databases in Azure we can have high availability. REINSTATE REQUIRED is present only after fast-start failover has occurred and shows on both the new primary database and the database undergoing reinstatement. created under this directory by DGMGRL will also have the same permissions. The broker will not allow a switchover to a standby that has an apply delay configured (DelayMins property is set to a non-zero value). Among many benefits of using this utility, I highlight that while using it, it will not need manual intervention to recover the databases or eventually a switchover in case the primary database becomes unavailable. DG_ADMIN environment variable is not set, the files are stored in Then the STOP OBSERVER command can be issued successfully on the former master observer. Table 6-3 FS_FAILOVER_OBSERVER_PRESENT Column of the V$DATABASE View, The master observer is currently connected to the local database, The master observer is not connected to the local database. Verify there are no active users connected to the databases. Both Cloud Control and the DGMGRL CLI will do this automatically as part of failover. During a switchover, the primary database transitions to a standby role, and the standby database transitions to the primary role. A complete failover can occur without any data loss, depending on the destination attributes of redo transport services, but an immediate failover usually results in some data loss. To move the observer to another computer: There is no need to disable fast-start failover when you move the observer. 11.2 rac servicefailover 2020-01-28 ORACLE ORACLE RAC/ASM RAC112. An alternative is to enable flashback database on the primary (and the standby if desired) so in the event of a failover, the primary can be flashed back to the time before the failover and quickly converted to a standby database. In order to maintain separation of Broker and non-Broker activity, a second static service is recommended. For example: Fast-start failover occurs if both the observer and the target standby database lose connection to the primary database for the period of time specified by the FastStartFailoverThreshold configuration property. If a database must be re-created from a copy of the new primary database, it will have the following status: Re-create the standby database from a copy of the primary database and then reenable it, as described in How to Re-create and Reenable a Disabled Database. When a switchover is started, the primary and standby databases that are involved should have as small a redo lag as possible. Determining a Database's Readiness to Change Roles. A single-instance database must be registered with Oracle Restart in order to publish FAN events via ONS. Installing and starting an observer is an integral part of using fast-start failover and is described in detail in the following sections: Oracle Data Guard Installation explains that you can either install only the Oracle Client Administrator or you can install the complete Oracle Database Enterprise Edition or Personal Edition on the observer system. The following paragraphs describe the supported availability modes. Oracle Data Guard helps you change the role of databases between primary and standby using either a switchover or failover operation. The act of switching roles should be a well-planned activity. STOP OBSERVING [cfg_group_name] stops LOCAL observers running on this host (where this DGMGRL is running) for all broker configurations in a specified group. These requirements are supplemental to those described in the documents previously referenced and in the following client-specific guides: Oracle Data Provider for .NET Developer's Guide for Microsoft Windows.